Grinding wheel dresser



May 5, 1942- H. N. sEYl-ERTH ET AL 2,281,719

GRINDING WHEEL DRESSER Filed July 26, 1938 8 Sheets-Shea?l l [NVE TO 2x/lfd M644, Y I 9% M TORNEIS.

May 5, 1942.

H. N. SEYFERTH ET AL 2,281,719

GRINDING WHEEL DRESSER Filed July 26, 1938 8 Sheets-Sheet 2 liu 227 IK( 2z-9 250 MMLWI m. (A TTONE YS.

May 5, 1942*.

H.N. sEYFERTH ETAL 2,281,719

GRIDING WHEEL DREssER Filed July 26, 1938 8 Sheets-Sheet 3 2&5'

BY fa -l "all, l TORNEI/s.

May 5, 1942- H. N. sEYr-ERTH Erm. 2,281,719

GRINDING WHEEL DRESSER Filed July 2e, 1938 n 8 sheets-sheet 4 5 a er.'

from/Era May 5, 1942 H. N. sEYFERTH ETAL 2,281,719

GRINDING WHEEL DRES SER May 5, 1942- H. N. sEYFERTH ET AL- y 2,281,719

GRINDING WHEEL DREssER 8 Sheets-Sheet 6 Filed July 26, 1938 [N VENTORS n fari/ el.'

BY Ira May 5,` 1942.

H. N. SEYFERTH ETAL 2,281,719.

GRINDING WHEEL DRESSE K Filed July 26, 1938 8 sheets-sheet v May 5., 1942- N. sl-:YFERTH ETAL 2,281,719

GRINDING WHEEL DRESSER ,aar

M T ORNE YS.

Patented May 5, 1942 GRINDING WHEEL DRESSER Harold N. Seyferth, East Detroit, and Ira J. Snader, Detroit, Mich., assignors to Ex-Cell-O Corporation, Detroit, Mich., a corporation of Michigan Application July 26,

22 Claims.

The invention relates generally to rgrinding machines embodying a grinding wheel and it has particular relation to a dresser for dressing the surface of the wheel.

As a generality, it will be understood that grind- 1 ing machines employing form. grinding wheels are utilized to generate forms on diierent types of Work. In particular, the present invention is concerned principally with thread grinding machines having grinding wheels designed to generate a thread on the Work, and an important reason for using such machines is to obtain precision in the formation of the threads. During the use of such grinding Wheels, wear on the grinding surfaces naturally occurs and it is customary to dress such surfaces by means of diamond dressing tools, so as to promote uniformity in precision obtained. Inasmuch as the dressing operation is not a work producing operation, it is important that the former be performed rapidly and with minimum interference with the work grinding operation so that the work producing capacity of the grinding machine will be as great as possible.

One of the principal objects of the invention is 1938, Serial No. 221,374

( (KCl. 12S-11) to provide a machine for dressing form generat- Another object of the invention is to provide ,y

an improved machine for dressing a thread generating form` on a grinding wheel which employs a pair of diamond dressing tools that are designed and arranged to dress respective grinding surfaces of the wheel.

Another object of the invention is to provide a dressing machine of the general type indicated wherein each of the diamond dressing tools, at the end of its particular dressing operation, is separated from the dressed surface and then is returned to its original position While being maintained in spaced relation to the dressed surface.

Another object of the invention is to provide a dressing machine such as mentioned, which is controlled and operated hydraulically.

Another object of the invention is to provide a. form dressing machine which is so designed, constructed, and arranged that by means of a readily variable relation of parts, the machine may be used from dressing grinding wheels varying widely in form or contour.

Other objects of the invention will become apparent from the following specification, from the drawings relating thereto, and fromv the claims hereinafter set forth.

For a better understanding of the invention, reference may be had to the accompanying drawings, wherein:

Figure 1 is a view in perspective of a. thread dressing machine constructed according to one form of the invention;

Fig. 2 is a front elevational View of the machine shoWn by Fig. 1;

Fig. 3 is a rear elevational view of the machine shown by Fig. l;

Fig, 4 is a side elevational view of the machine shown by Fig. 1, with certain parts shown in section;

Fig. 5 is a. cross-sectional view taken substantially along the line 5--5 of Fig. 2;

Fig. 6 is a cross-sectional view taken substantially along the line 6-6 of Fig. 5;

Fig. 7 is a cross-sectional view taken substantially along the line 'I-I of Fig. 6;

Fig. 8 is a cross-sectional view taken substantially along the line 8-8 of Fig. 2;

Fig. 9 is a cross-sectional view taken substantially along the line 9 9 of Fig. 8;

Fig. l0 is a cross-sectional view taken substantially along the line III-IU of Fig. 8;

Fig. 11 is a fragmentary, sectional view of the outer peripheral portion of a thread grinding Wheel, showing the manner in Which the surfaces of the wheel are dressed during operation of the machine; and

Figs. 12, 13, and 14 are sectional views of the valve employed for controlling operation of the machine.

Fig. 15 is a detail view in section showing the mounting of the diamond holder and the manner of adjusting it.

Referring to Figs. 1, 2, and 3, a fixed base portion of the grinding machine is indicated at I0 and the entire dresser shown by these figures is so mounted on this base portion that the grinding wheel may be brought into a proper position to be dressed in the manner hereinafter to be stated. A slide Il is on the base I0 by means of a dovetail I2 and slot I3 receiving the dovetail and the slide may be adjustably xed in position by means of a gib I4 at one side of the slot. This gib is adapted to be forced against one side ol the dovetail by means of a screw I5 threaded through a portion of the slide and which has its s fr.

Il, on the outer end of the screw, locks the latter in position after the adjustment is made.

As shown by Figs. l and 2, the slide ll has a concentric guideway i8 which receives a complementary guide I9 on a bracket swivel 2U, and as shown by Figures 1 and 5, the base of this swivel has three spaced, arcuate slots 22, 23, and 24 that are concentric to the guideway. The swivel is adjustably secured to the slide Il by means of bolts 25 projecting through the slots and threaded into the slide and by loosening the bolts slightly, the swivel may be swung about the center of the guideway and then by tightening the bolts, the swivel may be fixed in its new position.

In order to secure a ne adjustment of the swivel on the slide, an arcuate bar 2'l is secured to the slide, as shown by Figs. 3, 4, and L5, and this bar, as shown by Fig. 4, has teeth 28 on its inner edge which are engageable with teeth 29 on a pin 30 journaled in an adjacent portionv of the swivel. At its upper end, the pin 3K] has wing portions 3l and 32 through which, respectively, screws 33 and 34 are threaded. As seen by Fig. 4, the inner ends of these pins are adapted to abut a side surface of the swivel and it will be apparent that by loosening one of the screws and tightening the other, the pin 3D will be turned accordingly. This will enable moving the swivel relative to the slide Il owing to the engagement of the teeth 28 and 29. A fine degree of movement of the swivel may be obtained in this manner and the amount of movement may be indicated on bar 2l by employing a marker 35 on the swivel.

It will be understood that the bolts 25 must be loosened before adjusting the positions of the screws 33 and 34 to obtain the fine degree of movement, and ordinarily, the swivel will be so positioned that any movement desired can loe accommodated by adjustment of the screws 33 and 34. Should a greater movement be desired, or should it be desired to change the position of the swivel substantially, the pin B may be withdrawn and then reinserted after moving the swivel approximately to its new position.

As shown best by Figures l and 4, the swivel has an outwardly open and concentric guideway 31 and this guideway receives a similarly shaped dovetail 38 on a U-shapebracket 40. The bracket 4i) may be adjustably locked in position relative tothe swivel 2li by one or more screws 4I as shown by Figure 3, which are threaded through a side portion of the swivel and into the guideway 3l, so as to frictionally engage at their inner ends one side of the dovetail 38. Thus, by loosening the screws slightly, the bracket may be adjustably swung in a vertical plane, andi then locked in its new position by tightening the screws.

Now referring to Figures 2 and 5, in particular, it will be noted that a lead screw 45 extends between the ends of the bracket 40 and has its ends projecting into openings in such ends of the bracket. As shown by Figures 8, 9, and 10, one end of the screw at its under side has a wedge shape slot or groove 49 which receives a similarly shaped projection 50 on a sleeve 5l slidably mounted in an opening 52 in the adjacent end of the bracket. This arrangement prevents rotation of the lead screw about its own axis and it is also apparent that longitudinal movement of the lead screw will depend upon the position of the sleeve 5I along its own axis. If the sleeve is suiciently moved in one direction, the projection 53 will completely ll the slot 49 in the screw and thus prevent any movement of the screw longitudinally of its axis while if the projection 56 and sleeve are moved in the other direction, the projection will move towards the larger end of the slot and thus create a space between the projection and the sides of the slot that will permit longitudinal movement of the screw. Rotation o the sleeve about its own axis is prevented by means of a key 54 having a projection 55 that projects into a groove 53 in the under side of the sleeve. It may be noted that the tapered sides of the slot 49 and the tapered sides of the wedge shape projection E@ are substantially symmetrical to the aXis of the threaded pin 6I and from this it follows that if the screw 6| is adjusted to eect withdrawal movement of the projection from the slot, the space created between one tapered side of the projection and the adjacent tapered side of the slot will be substantially equal tothe space created between the opposite tapered side of the projection and the tapered side o the slot adjacent thereto.

In order to adjust the position of the sleeve 5I, it has a threaded opening til at one end and a threaded pin 6l is threaded into the opening. The pin at its outer end is journaled in a bushing 62 threaded into the bracket and the outer end of the pin is secured to a knob 63. At its opposite end the sleeve 5l has an opening 64, and a spring 65 seated in this opening and in an apertured cap 66 threaded into the opening in the bracket normally urges the sleeve 5l to the left, as seen in Fig. 8, so as to take up any looseness or play that may be present. When the knob 63 is turned, the sleeve is moved in one direction or the other, depending upon the direction the knob is turned, and movement of the sleeve, as previously stated, causes the wedge 5i! to move in the slot 49 in the feed screw 45. The knob 63 has suitable graduated indicia thereon adapted to cooperate with a marker on the bushing 62 so that the permitted movement of the lead screw may be calibrated.

Now referring to Fig. 5, the lead screw 45 has an intermediate threaded portion l@ and a sleeve 1| is slidably mounted on opposite and smooth portions of the lead screw and has an internally threaded portion 12 at its center which engages the thread on the screw. The opposite ends of the sleeve have close but slidable bearing contact with the smooth portions of the screw and the threads on the screw and sleeve are formed accurately so as to obtain accurate movement when the sleeve is rotated. The sleeve li is rotatable in and carries a body 'i3 that is movable along the screw with the sleeve, but which is prevented from rotating therewith by means presently to be described. This body has ring portions 'I4 and i5 disposed around opposite end portions of the sleeve and since the parts arranged between each ring portion and the end of the sleeve are substantially the same, a detailed description of such parts at one end of the sleeve only seems to be sufficient. Referring to the left hand of the arrangement as seen in Fig. 5, the ring portion 'I4 carries an outer bearing race 'i5 which is held in position by means of a bearing nut 'il threaded into the ring and engaging the race. In order to obtain a completely circumferential contact between the nut and the race 16, a malleable ring 18, constructed of brass, for example, is disposed in a shallow groove in the nut 11 and between the latter and the bearing race. It is evident that the malleable character of the ring 18 will allow it to change in contour under pressure as thenut is threaded into the ring portion 14 and thus obtain a completely circumferential metal to metal contact between the nut and the bearing race. A second nut 80 is threaded into the ring portion and against the nut 11 and between such nuts, a sealing ring 8| may be provided to prevent the escape of lubricant that is provided in the bearing.

The sleeve 1| carries an inner bearing `race 83 and between the two bearing races balls 84 are provided. The race 83 is held in position by means of a nut 85 threaded over to the sleeve 1|. It will now be apparent that the sleeve 1| may turn in the body while at the same time being movable therewith axiahy of the lead screw.

Axially outward of the nut 85, a cam 88 is mounted on the end of the sleeve and this cam is maintained against the end of the nut by means of a friction disc 89 and a nut 90 threaded on the end of the sleeve. The friction disc 89 has a key 9| at one point which is slidable in a keyway 92 formed in the end of the sleeve, from which it follows that the friction disc is prevented from rotating relative to the sleeve 1l. It may be mentioned that the cam 38 may be adjusted circumferentially upon loosening the nut 90. While the opposite end of the sleeve 1| and the ring portion 15 have similar elements assembled therewith, as described previously with respect to the other end of the sleeve, the cam on the right end of the sleeve has a different function as compared to the cam 98 and for this reason is identified by a different numeral 95.

Between the ring portions 14 and 15, the body 13 has a semi-circular portion |00, which is recessed as indicated at I for receiving a worm wheel |02 disposed on an intermediate portion of the sleeve 1|. While the worm wheel |02 is rotatable relative to the body it is held against axial movement relative thereto by means of finished guide surfaces |03 and |04 slidably tting opposite faces of the Worm wheel. A driving connection is obtained between the worm wheel and the sleeve 1| by means of keyways |05 and |06 in the sleeve 1| and wheel, respectively, and a key |01 disposed in both keyways.

Now referring to Fig. 4, the body 13 at the lower side of the lead screw, is provided with spaced walls |08 and |09 that straddle a guide block ||0 that is secured by bolts to an upwardly projecting web I I2 on the bracket 40. Between the guide block ||0 and the wall |09, a bar ||3 is provided which is adapted to be held against the guide block in such manner that a desired friction may be provided between the guide block and the bar.

As seen in Fig. 2, three screws ||1, H8, and ||9 are threaded into the wall |09 and Viewing Fig. 4 in conjunction with Fig. 2, the screws ||1 and I9 are relatively short and hold compression springs |20 against the bar l |3. The intermediate screw IIB has a pilot |2| at its inner end which projects into an opening in the bar ||3 so as to hold the latter relative to body 13 during movement of such body on the guide block while still permitting the bar to be pressed against the guide block by the springs. It will be appreciated that this spring pressure also results in the wall |08 being similarly pressed into frictional contact with the guide block ||-0. The purpose body 13- along the guide block is to prevent movementof the body and associated mechanism along the axis of the lead screw until the latter will rst have shifted longitudinally the amount, if any, allowed by the adjustment described in connection with Figs. 8, 9, and l0. As will be understood, the degree of frictional resistance necessary may be obtained by providing a suitable dimension of springs.

Considering the mechanism so far described, it will be apparent that if the worm wheel is rotated, the parts assembled on the lead screw will move longitudinally thereon after overcoming the friction between the bar ||3, wall |08, and the guide block H0, it being understood that this frictional resistance is such that before any movement of the assembly along the lead screw axis occurs, the lead screw itself will move longitudinally the amount permitted by the adjustment described in connection with Figs. 8, 9, and 10. After the lead screw has moved thisk limited amount, then continued turning of the worm wheel will cause the assembly on the screw to travel along the latter, during which the frictional force pressing the bar against the block ||0 is overcome.

Still referring to Fig. 4, the worm wheel |02 is adapted to be rotated by means of a worm |25 that is keyed to a shaft |26 journaled in a cap |21 which ts between the ring portions 14 and 15 of the body and which is secured to such body by means of screws |30 (shown in cross-section by Fig. 5). Shaft |26 is driven by a hydraulic motor comprising mating gears |3| and |32 on the shaft |26 and on an auxiliary shaft |33, respectively. It may be mentioned that the gears are disposed in openings in a spacer |35 located between the cap |21 and a bearing bracket |31, in which the outer ends of shafts |26 and |33 are journaled,

The hydraulic lines leading to the hydraulic motor and to opposite sides of the motor gears, respectively, are generally indicated at |40 and 4| in Fig. 6. It is to be understood that these lines or openings extend longitudinally in cap |21 and into the motor spacer |35, and while not shown, the openings or lines |40 and |4| are connected to vertical openings in cap |21 which join openings |42 and |43, respectively, in the body 13 as seen in Fig. 5. Any leakage of fluid in the motor and along the driven shafts drains through openings leading to various points where leakage may occur and such openings are connected to a drain line |45.

Referring to Figs. 4 and 5 jointly, the three openings |42, |43, and |45 all lead to a valve, generally indicated at |50, and it is to be understood that the drain line |45 is constantly connected to an exhaust port in the valve. The lines |42 and |43 alternately are pressure and exhaust lines so that when hydraulic fluid under pressure is connected to one line, the other line is open to exhaust and it follows thatl when one of the lines is connected to the uid under pressure, the hydraulic motor will rotate in one direction and when the other line is connected to the fluid under pressure, the motor will rotate in the opposite direction. While the manner in which the mechanism is to be controlled by operation of the valve will presently be described, it is desired at this time to direct attention to the provision of plungers |58 and |59, as shown by Fig. 3, which have lower inclined faces |56 and |51 adapted to engage a plunger in the valve. These plungers |58 and |59 have their upper ends disposed in the path of movement of bell crank trips |6| pivotally mounted on the body 13 and which have ends |62, respectively, disposed in the path of movement of pins |65 and |66 on cams 88 and 95. These pins are circumferentially spaced so that one pin moves one trip while the other is substantially displaced from its trip.

Now referring to Figs. 2, 6, and 7, it will be observed that the lower part of the body 13 has a pair of spaced openings |15 and |16 in which diamond carriers |11 and |18 are reciprocably mounted. Each of the carriers as shown by Fig. 7 has a threaded opening |86 and a spring receiving bore |8I, and the openings, respectively, in the two carriers receive adjusting bolts |82 and |83 that are threaded into the openings |86. A spring |85 in each of the bores 8| abuts at one end a shoulder at the inner end of the bore |86 and at its other end a cover plate |86 secured to the body 13, and serves to constantly urge the carrier forwardly. The outer end of each of the bolts |82 and |83 passes through an opening in the plate |86 and is provided with graduated indicia |96 adapted to cooperate with a marker on the plate |86, so that turning movement of the bolts may be measured or calibrated.

At the forward end of each of the carriers as shown by Figs. 7 and 15, an angled opening |9| is provided and these openings, respectively, receive diamond holders |92 and |93 having pointed diamonds |94 and |95, respectively. A set screw 96 is used in conjunction with each of the carriers for holding the diamond carrier against turning about its own axis. Each of the diamond holders has an inclined, rear end face |91, against which the end of the cooperating adjustment bolt abuts, and from this it will be apparent that when the bolts |82 and |83 are turned, so as to move the bolts forwardly, the diamond holders will be advanced in the angled openings. Since the openings are angled toward each other, as best shown by Fig. 2, this adjustment of the bolts |62 and |83 will advance the diamond points along converging lines.

As shown by Figs. 6 and '1, the carriers 11 and |18, respectively, have oifset arms 266 and 26| at their rear ends, and each of these terminates in a tubular portion 262 extending parallel to the bores |15 and |16. Bushings 263 and 264 are tted in the tubular portions 262 and are xed in position by means of set screws 265. Within the bushing 263, a cam follower 266 is reciprocably mounted and the forward end of this f ollower engages the peripheral face of the cam 88. A bolt 268 provided with graduations 269, threaded into the rear end of the bushing 263, serves to adjust the position of the cam follower with respect to the carrier |11.

Similarly, the bushing 264- carried by the arm 26| has a cam follower 2|6 which engages` the peripheral face of the cam` 95. A second bolt 2|2, shown by Fig. 5, is adjustably threaded into the bushing 264 so that the position of the cam follower 2 |6 may be adjusted with respect to the carrier |18,

Again referring to Fig. 6 in particular, it will be observed that the carrier |11 is urged against a block 226 by means of a spring pressed plunger 22| and that this block 226 is to the left of the axis of bolt |82 in carrier |11. With respect to carrier |18, it will be noted that the arm 26| thereof is urged against a surface 222 by a spring pressed plunger 223. The reason for these spring pressed arrangements may be stated briefly as follows. It will be apparent that due to the offset relation of the cam followers 266 and 2| 6 with respect to the carrier openings |15 and |16 in body 13, engagement of the two cams 88 and 95 with such cam followers will tend to turn the carriers |11 and |18 about the axes of such openings. As will be more evident hereinafter, diamond |54 is engaged with the grinding wheel when cam 88 is turning counterclockwise, as seen in Fig. 7, and hence the frictional engagement of the cam with the cam follower 266 tends to hold the arm 266 positively against the block 226, as seen in Fig. 6. Thus, a solid anchor is provided against altering the position of the diamond during its cutting operation. On the other hand, when the diamond is cutting the grinding wheel, cam 95 is turning clockwise, and the frictional engagement of the cam with the cam follower 2|6 holds the arm 26| solidly against the surface 222.

As shown by Figs. 1 and 4, a cap or cover 225 is provided over the body 13, and this cover is held in position by bolts 226 and 221 threaded into cap |21. These bolts also secure a bar 228 in position that carries a block 229 which is apertured for the purpose of conducting coolant therethrough. A coolant inlet 230 communicates through the block with pipes 23| and 232 which extend to points adjacent the diamonds |94 and |95 so as to supply coolant to the diamonds and grinding wheel during the wheel dressing operation.

It may be pointed out in connection with Fig. 2 that adjustment of the bracket 46 on the bracket swivel 26 occurs about an axial center line indicated at 234, which is centered with respect to both diamonds |94 and |95 and thus adjustment of the bracket causes both diamonds to move about this axial center line. This adjustability, in conjunction with the adjustability of the bracket swivel and the slide enables locating the diamonds in the desired positions.

Generally it will be realized that the path of movement of either of the diamonds is governed jointly by travel of the assembly along the lead screw, the shape of the controlling cam, and by the endwise movement of the lead screw. The latter movement will govern the path of movement of the diamonds in that the amount of such end movement of the lead screw will govern the time at which axial progression of the diamonds begins, and thus will determine the location of such paths laterally of the grinding wheel. Diiferently shaped cams may be employed and readily substituted one for another in order to obtain the desired radial movement of the diamonds and the pins on the cams for controlling operation of the motor may be varied in position depending on the results to be obtained. Moreover, the cams may be relatively displaced circumferentially as desired in order to vary the relation of movement of the diamonds. Again, the relation of axial movement to radial movement may be varied by using a lead screw arrangement with threads of a different pitch or combining this variation with variations in the cams.

In the construction as shown, the cams will not be turned through a complete turn as the pins will reverse 0r stop the motor before this occurs. Such pins are so related, however, and the cams are so arranged and shaped that as one diamond is moving toward the axis of the grinding wheel, the other is moving away from such axis. The general operation and the character of movement of the diamonds may best be understood in connection `with Fig. 11, which shows a grinding wheel 235 and the two diamonds |94 and |95 diagrammatically. It may be mentioned before describing this operation that the shape of the cams necessary to obtain the desired movements of the diamonds may readily be obtained by those skilled in the art. Also, it may be stated that the dressing operation preferably is effected with the grinding wheel operating at the same high rate of speed as that used in the work grinding operation, as then the form is more accurately dressed and moreover, it is not changed such as might be caused by a change in centrifugal forces.

As seen in Figure ll, the two points 250 and 25| indicate, respectively, the initial positions of the diamonds |94 and |95, that is, the position of each diamond prior to the beginning of its wheel dressing movement. Assuming that the diamond |95 is at the starting point 250, the diamond |99 will be approximately in the position shown by full lines and indicated at 252. Assuming also that the lead screw is under an adjustment which permits certain endwise movement thereof before the mechanism thereon travels axially of the screw, the diamond |95 will not move until the screw is shifted endwise the amount permitted, as the cam 95 at this time engages its cam follower along a substantially circular portion of the cam. After the lead screw is shifted endwise, the diamond will travel axially of the lead screw until said circular portion of the cam passes its cam follower and then the diamond will travel inwardly towards the center of the grinding wheel along the path 253. The cam is of such character then that the diamond will follow the path 253 so as to dress the Lipper side of the wheel, as seen in this figure. When the diamond |95 reaches the end of its movement, indicated by the numeral 255, the hydraulic motor reverses and then the lead screw is shifted in the reverse direction the amount permitted. During shifting of the lead screw, rotation of the cam moves the diamond in a radial direction substantially to the point indicated at 256. When this point is reached, the mechanism carrying the diamond begins to move axially of the lead screw along the path indicated at 251, andin this connection it will be appreciated that the diamond is separated substantially from the surface of the wheel. While the diamond |95 is moving inwardly to dress the wheel in the mannermentioned, the diamond |94 is returning along its return path .of movement, indicated at 258, and it will reach the position indicated at 25| at about the time the diamond |95 reaches the position indicated at 255. The line indicated at 299 shows the path of movement of diamond |94 during its wheel dressing movement and it will be understood that this movement occurs as diamond |95 is returning. Assuming now that the lead screw adjustment is changed so that `a greater end movement of the screw is required before movement of the mechanism along the lead screw axis occurs, it will be apparent that the diamond |95, for example, will stay stationary for a longer period of time and therefore a larger circular portion of the cam will passthe cam follower, and from this it will be evident that the diamond will start moving inwardly along a different line such as the line indicated at 252, It follows that the entire path of movement of the diamond will shift laterally of the grinding wheel so as to correspond with the shift from line 253 to 262.

Likewise, the path of `return movement V25`| will .shift laterally but it will be spaced farther from the path of dressing movement due to the greater radial movement at the beginning of the return movement. It follows that if the edge of the grinding wheel is narrower than desired, less endwise movement of the lead screw will be required, whereas if a wider edge on the grinding wheel is present, greater endwise shifting of the lead screw will be necessary. As a generality, therefore, it may be said that adjustability in shifting ofthe screw endwise enables bringing the two paths of dressing movement of the two diamonds closer together or moving them farther apart, as the case may be, without altering the contour of the paths of movement and while still causing the diamonds to be separated from the dressed surfaces of the wheel during return movement of the diamonds.

Since adjustment of the screw 6| and movement of the wedge 50 in the` slot 49 creates a space between one tapered side of the projection and the adjacent tapered side of the slot which is substantially equal to the space at the opposite side of the projection, it follows that any adjustment of the wedge 50 effects shifting of both paths of movement of the diamonds axially of the grinding wheel depending upon the adjustment made. Moreover, this shifting of the two paths of movement effected by changing the position ofthe wedge 50 in the slot 49 is substantially equal but in opposite directions. In other words, during anyvariation of the relative locations of the two paths of movement of the tools axially of the wheel, such paths are automatically maintained substantially symmetrical to a substantially fixed median plane transverse to the Ywheel axis, so that the tools may be adjusted relative to a substantially fixed wheel center plane in dressing wheels having differently spaced side surfaces.

I t may be mentioned that the Wheel shown in Fig. 1l has two inclined surfaces radially inward of the thread form and, in causing the diamonds to travel along these inclined surfaces, the diamonds automatically are resharpened or reshaped to provide new cutting points. This feature is disclosed and claimed in the application for patent of William Locke, Serial No. 212,019, filed June 6, 1938. The present machine is adapted not only to take care of dressing of the wheel form and returning the diamonds in spaced relation to the dressed surfaces, but also to effect this reshaping of the diamonds.

In using the wheel dressing machine, normally the grinding wheel will be dressed at the end of an operation performed by the work grinding machine and it is desirable that operation of the dresser be so controlled as to enable the operator to change the work in the grinding machine while the wheel dressing operation is being effected. The means for controlling operation of the dresser will now be described but before making a detailed description it may be stated generally that the control means is to operate as follows. With the dresser at rest, and with the diamonds located in initial positions 25|) and 252 as seen in Fig. 11, the dresser is started by moving a manual control and then it continues its operation automatically until the diamonds return to their initial positions where the dresser is stopped automatically. Thus, the operator need only move the manual control initially.

Now directing attention to Fig. l2, the valve |50 comprises a body 215, a main operating plunger 216 and an auxiliary plunger 211 within the main plunger. The bore in the body which slidably receives the plunger 216 is indicated at 218 and this bore has three exhaust ports 219, 280 and 28|, two pressure ports 282 and 283, two motor line ports 285 and 286 and a pressure port 281 adapted to be temporarily connected to a pressure line. Plates 290 and 29| shown in broken lines for the purposes of clarity and which are bolted to the ends of the body 215 serve as stops for plunger 216 and also provide guides for the operating plungers |58 and |59 described previously.

The plunger 216 has a bore 293 receiving the auxiliary plunger 211 and at its outer surface plunger 216 also has three principal grooves 294, 295 and 296, two pilot line grooves 291 and 298, a drain groove 299 and a starting line groove 30|. Grooves 294 to and including groove 298 are connected by radial openings respectively to the bore 293. Plugs303 and 304 threaded into the ends of plunger 216 provide end stops for plunger 211 as well as closures for the ends of the plunger. At the right, a plunger 306 is slidable in the end of plunger 216 and the space at the inner end of plunger 306 is connected by an opening 301 to the bore 293 near the center of the latter. At the left end, a tubular plunger 3| 2 having an inner end wall is slidable in the end of plunger 216, and a second plunger 308 is slidable in plunger 3 I2. A pin 3|0 passing through the wall of plunger 216 limits outward movement of plunger 3|2 relative to plunger 216. The space at the inner end of plunger 3|2 is connected to bore 293 by an opening 3| and the space between the inner ends of plungers 308 and 3|2 is in communication with the starting pressure line 281. It may be added here that plates 290 and 29| also serve as stops to limit outward movement of plungers 308 and 306, respectively. Grooves 3 1 and 3| 8 are provided in plunger 211 for a purpose which will be understood hereinafter.

Pressure ports 282 and 283 are connected by passages not shown to a hydraulic line indicated at 320 in Fig. 3, exhaust ports 219, 280 and 26| are connected to an exhaust line 32| while the starting line port 281 is connected to a line 322. Line 322 as also shown by Fig. 3, extends to a remote control valve 323 which is operable manually. 'Ihe valve includes a body 321 having a plunger 328 slidable therein and such plunger normally is urged to the right by a spring 329 but is adapted to be moved against the spring by an external, hand control member 330. An exhaust line 33| connected to the body 321 normally is in communication with line 322 through the valve from which it follows that port 281 normally is open to exhaust. A hydraulic line 332 leading to the valve is adapted to be placed in communication with line 322 when the plunger is moved to the left, by a groove 333 in the plunger, it being evident that the plunger when so moved to the left cuts off line 322 from line 33|. It may be noted that both ends of the plunger are open to exhaust at all timesby means of an opening 334 extending axially of the plunger and smaller openings 335 at the right end of the former. The size of openings 335 may be such if desired, to slightly retard spring return of plunger 3|8 so as to hold port 281 in communication with line 332 for a short length of time after hand pressure on the member 330 is released.

Motor line ports 285 and 286 respectively are connected to the lines |43 and |42 leading to oplli) posite sides of the hydraulic motor, and with the parts in position as'shown in Fig. 12, both ports 285 and 286 are connected with the exhaust groove 295 and, therefore, the motor is stopped and there is no chance of it being moved slightly by any leakage of fluid under pressure to either port. When it is desired to start the cyclic operation, the valve 323 (Fig. 3) is operated and this temporarily admits fluid under pressure to the interior of plunger 3|2 and this causes the latter to shift to the right. At this time, fluid under pressure is present beyond the inner end ofv plunger 3|2 and thus the uid therein acts as a hydraulic column, resulting in movement of plunger 216 along with plunger 3|2. This movement connects pressure line 282 and groove 294 to the motor port 285 and connects motor port 286 to exhaust groove 295 and exhaust port 280. The motor thus is caused to rotate in one direction.

When plunger 216 has moved to the right end position as shown by Fig. 13, pressure port 282 opens slightly to groove 291, and pressure is supplied to the left end` of auxiliary plunger 211 while the right end thereof is open to exhaust port 28|. Auxiliary plunger 211 is thus shifted to the right and when so shifted, the space at the right end of plunger 3 2 is connected by opening 3H and grooves 3|1 and 295 to exhaust port 280.

After the motor rotates sufciently, plunger |58 is caused to move downwardly by movement of cam 88, and the inclined surface |56 thereon (Fig. 3) engaging a chamfer 325 on the right end of plunger 216, shifts the latter slightly to the left and enough to connect pressure port 283 with groove 296 and hence space 3|8 and opening 301, thereby connecting the space at the inner end of plunger 306 with the fluid pressure line. I'his results in a shift of plunger 216 to the left to the position shown in Fig. 14, which in turn connects pressure port 283 to groove 296 and motor line 286, and exhaust port 280 to groove 295 and motor line port 285. This causes reversal of the motor.

At the end of the left hand movement of plunger 216, pressure port 283 is opened slightly to groove 298 and fluid pressure is thus supplied to the right end of plunger 211 while the left end of the latter is connected to exhaust. Thus auxiliary plunger 211 is shifted to the left and when so shifted, the space at the inner end of plunger 306 is connected by opening 301 and grooves 3|8 and 295 to exhaust port 280.y

When the motor has reversely rotated suiciently, cam eifects downward movement of plunger |59 which in turn engages a chamfer 326 on plunger 216 and shifts the latter slightly to the right suiciently to open pressure port 282 to groove 294 and opening 3| thus supplying uid under pressure to the right end of plunger 3| 2. This will force plunger 216 to the right until pin 3|0 engages the shoulder on plunger 3|2 and then the parts will stop in position. This brings the parts to the positions shown by Fig. 12.

Starting of the cycle may be re-initiated by operating valve 323, or a manual trigger 336 may be used to shift plunger 216 the initial amount. At both of the end positions of plunger 216, the spaces between its right end and plunger 306, and its left end and plunger 3|2 are open to exhaust and the plunger is held in position by friction only. For this reason the plunger is shiftable by a relatively small force which is normally advantageous for actuating purposes. In some installations however, where small exhaust lines vare used, the exhaust pressure may be considerable and in view of the difference in areas at such ends of the plunger, may be sufficient to shift the plunger at the improper time. For this reason the desired friction is introduced by a split wire ring 331 which creates enough resistance to movement of plunger 216 that the back pressure will not move the plunger.

While the valve is shown in detail, it is to be understood that such valve per se is not a part of the present invention. Electrical controls might be employed to secure the particular cyclic operation mentionedthat is manual start, automatic reversal of the motor, and then stopping of the motor at its initial position. It may be added that a metering valve might be used in the fluid pressure line to vary motor speed.

Although only one form of the invention has been illustrated and described in detail, it will be apparent to those skilled in the art that various modifications may be made without departing from the scope of the appended claims.

What is claimed is:

l. In combination, a frame, a non-rotatable screw means mounted in the frame, means permitting limited shifting of the screw means along its axis, rotary feed screw means movable along s,

and engaging the first screw means, a tool holder movable along said axis with the rotary screw means when the latter is rotated, means for reversing the rotation of said rotary screw means after a predetermined movement thereof along said axis so as to reverse the movement thereof along said axis, and means for effecting an axial shifting of said first screw means within the limits permitted when rotation of the rotary screw means is reversed.

2. In combination, a frame, non-rotatable screw means mounted in the frame, means permitting limited shifting of the screw means along its axis, rotary feed screw means movable along and engaging the first screw means, a tool holder movable along said axis with the rotary screw means when the latter is rotated, means for reversing the rotation of said rotary screw means after a predetermined movement thereof along said axis so as to reverse the movement thereof along said axis, means for effecting an axial shifting of said first screw means within the limits permitted, when rotation of the rotary screw means is reversed and means for adjusting the limits of permitted shifting movement of the rst screw means.

3. In combination, a frame, a lead screw mounted in the frame and having a threaded portion, an internally threaded sleeve on and having threaded engagement with the threaded portion of the screw, motor driven means for rotating the sleeve so as to cause movement of the latter along the screw, a tool holder movable towards and from the axis vof the screw, means including a cam turned by the sleeve for moving the tool holder as the sleeve moves along the screw, and means for controlling operation of the motor driven means including a control element on the cam.

4. In combination, a frame, a non-rotatable screw mounted in the frame and having a threaded portion, means permitting limited movement of the screw along its axis, an internally threaded and rotary sleeve on the screw and having threaded engagement with the threaded portion of the latter, 'a tool holder, means effecting movement of the holder with the sleeve along the screw when the sleeve is rotated, cam means rotated by the sleeve for moving the holder towards and from'the axis of the screw, reversible means for rotating the sleeve, and means for automatically causing a shifting of the screw along its axis within the limits permitted when rotation of the sleeve is reversed.

5. In combination, a frame, a non-rotatable screw mounted in the frame and having a threaded portion, means permitting limited movement of the screw along its axis, an internally threaded and rotary sleeve on the screw and having threaded engagement with the threaded portion of the latter, a tool holder, means effecting movement of the holder with the sleeve along the screw when the sleeve is rotated, cam means rotated by the sleeve for moving the holder towards and from the axis oi the screw, reversible means for rotating the sleeve, and means sufficiently resisting movement of the sleeve along said screw as to cause a shifting of the screw the limited amount permitted before movement of the sleeve along the axis can occur.

6. A dressing machine for dressing a grinding wheel, comprising a frame, a lead screw nonrotatably mounted in the frame and having a threaded portion and smooth portions at opposite ends of the threaded portion, a sleeve on the screw and having an internally threaded portion engaging the thread on the lead screw and. having end bearing portions slidably fitting the smooth end portions of the screw, means for rotating the sleeve, a tool holder, and means operatively connected to the sleeve for moving the tool holder towards and from the axis of the screw as the sleeve travels axially on the latter.

7. In combination, a bracket having spaced arms, a non-rotatable lead screw having its ends engaging the arms respectively, a threaded sleeve on the screw, means for turning the sleeve, a tool support carried by the sleeve, and cooperating means on the support and on the bracket for preventing turning of the support when the sleeve is rotated.

8. In combination, a bracket, a threaded member carried by the bracket, a second member having threaded engagement with the rst member, means for holding one of said members against rotation, means for rotating the other member, a tool carrying support carried by the rotatable member, means for preventing rotation of the support with the rotatable member while allowing its axial movement with the rotatable member, and adjustable means providing for variable resistance to axial movement of the support.

9. In combination, a bracket, a threaded member carried by the bracket, a second member having threaded engagement with the first member, means for holding one of said members against rotation, means for rotating the other member, a tool carrying support carried by the rotatable member, means for preventing rotation of the support with the rotatable member while allowing its axial movement with the rotatable member, means allowing predetermined endwise movement of the non-rotatable member, and adjustable means providing for adjustable resistance to axial movement of the support to enable securing endwise movement of the non-rotatable member when the rotatable member is reversely rotated.

l0. A dressing machine for dressing a grinding wheel which is rotated adjacent the dresser, which comprises rotary lead screw means disposed parallel to the axis of the wheel, a dressing tool carrier, non-rotatable means movable along the screw axis and by the rotary screw means and carrying the tool carrier, spring means constantly urging the tool carrier towards the wheel axis, and a cam rotatable by the screw means for governing movement of the carrier by the spring means.

1l. A dresser for dressing a grinding wheel comprising ra support having an opening, a reciprocatory diamond carrier disposed in said opening, an arm on said carrier, a cam follower on said arm, a rotary cam on the support in offs et relation to the center line of said opening and engaging said follower, and a bearing slidably engaging said arm so as to anchor said carrier against turning in a predetermined direction when the cam is turning in a direction normally tending to move the carrier in said predetermined direction.

12. A dresser for dressing a grinding wheel comprising a support having an opening, a reciprocatory diamond carrier disposed in said opening, an arm on said carrier, a cam follower on said arm, a rotary cam on the support in offset relation to the center line of said opening yand engaging said follower, a bearing slidably engaging said arm so as to anchor said carrier against turning in a predetermined direction when the cam is turning in a direction normally tending to move the carrier in said predetermined direction, and resilient means urging movement of said carrier in said predetermined direction.

13. In a dresser for dressing a grinding wheel, a bracket, a lead screw mounted in said bracket, and adjustable means permitting endwise movement of the screw in the bracket, said means comprising a wedge shaped slot in the screw, a similarly shaped wedge on the bracket and projecting into the slot and adjustable means for moving the wedge along the slot.

14. In combination, a bracket, a non-rotatable lead screw on the support, an internally threaded and rotatable sleeve on the lead screw, a tool support mounted on the sleeve for movement therewith axially of the screw, means for preventing rotation of the screw while permitting its axial movement with the sleeve, a tool controlling cam carried by the sleeve and rotatable therewith, and a movable tool holder carried by the support and controlled by said cam.

15. In combination, a bracket, a non-rotatable lead screw on the support, an internally threaded and rotatable sleeve on the lead screw, a tool support mounted on the sleeve for movement therewith axially of the screw, means for preventing rotation of the screw while permitting its axial movement with the sleeve, a tool controlling cam carried by the sleeve and rotatable therewith, a movable tool holder carried by the support and controlled by the cam, and means enabling circumferential adjustment of the cam on the sleeve.

16. A dressing machine for dressing a grinding wheel which is rotated adjacent the dresser, comprising a dressing tool carrier, spring means for moving the carrier towards the wheel. axis, a rotary cam for controlling the movement of the carrier by the spring during the wheel dressing operation and for withdrawing the carrier againstv the action of the spring after the dressing operation is completed, means for moving the carrier axially of the Wheel during the wheel dressing operation, and means automatically effecting simultaneous operation of the last means and the rotary cam.

17. A dressing machine for dressing a rotary grinding wheel having its outer peripheral portion substantially V shape, comprising a pair of dressing tools, a support for each tool, means effective to advance one tool and its support inwardly towards the grinding wheel axis and along one side surface of the V shape peripheral portion to effect dressing of said side surface, means effective to move the other tool and its support inwardly towards the wheel axis and along the other side surface of the V shape peripheral portion to effect dressing of such other side surface, and a single adjustable means for varying the relative locations of the two paths of movement of the two tools so that grinding wheels having variably spaced side surfaces may be dressed, said adjustable means being so constructed and arranged that adjustment effects shifting of both paths of movement either towards or away from each other axially of the grinding wheel depending upon the adjustment made.

18. A dressing mfachine for dressing a rotary grinding wheel having its outer peripheral portion substantially V shape, comprising a pair of dressing tools, a support for each tool, means effective to advance one tool and its support inwardly towards the grinding wheel axis and along one side surface of the V shape peripheral portion to effect dressing of said side surface, means effective to move the other tool and its support inwardly towards the wheel axis and along the other side surface of the V shape peripheral portion to effect dressing of such other side surface, and adjustable means for Varying the relative locations of the two paths of movement of the tools axially of the wheel while automatically maintaining the paths substantially symmetrical to a substantially xed median plane transverse to the wheel axis so that the tools may be adjusted relative to a substantially fixed wheel center plane in dressing wheels having differently spaced side surfaces.

19. A dressing machine for dressing a rotary grinding wheel having its outer peripheral portion substantially V shape for thread grinding purposes, which comprises a pair of dressing tools, a support for each tool, means effective to move one tool and its support axially of the wheel and then inwardly towards the grinding wheel axis an-d along one side surface of the V shape peripheral portion to effect dressing of said side surface, means effective to move the other tool and its support along the wheel axis and then inwardly towards the wheel axis and along the other side surface of the V shape peripheral portion to eifect dressing of such other side surface, and adjustable means for varying the relative axial locations of the inward portions of the two paths of movement of the tools while maintaining them substantially symmetrical to a median wheel center plane transverse to the wheel axis so that the tools may be adjusted relative to a substantially xed wheel center plane in -dressing wheels having differently spaced side surfaces.

20. A dressing machine for dressing a rotary grinding wheel having its outer peripheral portion substantially V shape for thread grinding purposes, which comprises a pair of dressing tools, a support for each tool, means effective to move one tool and its support axially of the wheel and then inwardly towards the grinding wheel axis and along one side surface of the V shape peripheral portion to effect dressing of said side surface, means effective to move the other tool an-d its support along the wheel axis and then inwardly toward the wheel axis and along the other side surface of the V shape peripheral portion to eiect dressing of such other side surface, and adjustable means for modifying both paths of movement of the tools while automatically maintaining the paths substantially symmetrical to a substantially fixed center plane directed radially of the Wheel axis.

2l. A dressing machine for dressing a rotary grinding wheel having its outer peripheral portion substantially V shape, comprising a pair of -dressing tools, `a support for each tool, means effective to advance one tool and its support-inwardly toward the grinding wheel axis and along one side surface of the V shape peripheral portion to eifect dressing of said side surface, means eifective to move the other tool and its support inwardly toward the Wheel axis and along the other side surface of the V shape peripheral portion to effect dressing of such other side surface, and adjustable means for modifying both 20 metrical to a substantially fixed center plane directed radially of the Wheel axis.

22. A dressing machine for dressing a rotary grinding Wheel having its outer peripheral portion substantially V shape, comprising a pair of dressing tools, a support for each tool, means effective to advance one tool and its support in- Wardly towards the grinding Wheel axis and along one side surface of the V shape peripheral portion to effect dressing of said side surface, means effective to move the other tool and its support inwardly towards the Wheel axis and along the other side surface of the V shape peripheral portion to effect dressing of such other side surface, and a single adjustable means for automatically varying the two paths of movement of the tools while maintaining such paths substantially symmetrical to a predetermined plane directed transversely to the wheel axis.

HAROLD N. SEYFERTH.

J. SNADER. 

